This is Steven Salzberg's blog on genomics, pseudoscience, medical breakthroughs, higher education, and other topics, including skepticism about unscientific medical practices. Here's where I can say what I really think about abuses and distortions of science, wherever I see them.

The first study is a large review by Philippe Autier and colleagues, who found that taking supplemental vitamin D has no effect on a wide range of diseases and conditions. After looking at over 450 studies, the authors conclude:

“The absence of an effect of vitamin D supplementation on disease occurrence, severity, and clinical course leads to the hypothesis that variations [in vitamin D levels] would essentially be a result, and not a cause, of ill health.”

So it appears that we’ve been getting cause and effect backwards, at least as far as vitamin D is concerned. Autier looked at non-skeletal disorders, including heart disease, weight gain, mood disorders, multiple sclerosis, and metabolic disorders, all of which have been linked to lower vitamin D. In trial after trial, supplemental vitamin D had no beneficial effect on any of these conditions. Autier et al concluded that:

“associations between 25(OH)D and health disorders … are not causal. Low 25(OH)D [vitamin D] could be the result of inflammatory processes involved in disease.”

Instead, the researchers found, in study after study, that low vitamin D was the result of poor health, not the cause.

The Autier study didn’t look at the biggest supposed benefit of vitamin D: protection against osteoporosis. We’ve long known that vitamin D is associated with bone health. Fortunately, in the same issue of The Lancet, Ian Reid and colleagues looked closely at this question. They reviewed 23 studies with 4082 participants, all designed to determine at whether supplemental vitamin D improves bone density. Their findings? It doesn’t help. They concluded:

“Continuing widespread use of vitamin D for osteoporosis prevention in community-dwelling adults without specific risk factors for vitamin D deficiency seems to be inappropriate.”

Vitamin D supplements, to put it plainly, are a waste of money.

(For those concerned about osteoporosis, the widely used drug alendronate (Fosamax®), has been shown to increase bone density by about 5%, as explained in a 2011 article by Dr. Sundeep Khosia. But Fosamax has side effects.)

It’s pretty easy to get enough vitamin D in a normal diet. Or, as Dr. Mark Gillinov explained in the Huffington Post last week, just 10 minutes of sunlight gives you about 4 times your daily recommended vitamin D requirement.

So here's my expanded list of the Top Six Vitamins You Shouldn’t Take, with the newest entrant at the end:

What’s left? Well, if you don’t have a deficiency, there’s no reason to take any supplemental vitamins at all. As my Hopkins colleagues Eliseo Guallar, Lawrence Appel, and Edgar Miller wrote last month in the Annals of Internal Medicine : “Enough is enough: stop wasting money on vitamin and mineral supplements.” As they wrote, after looking at three more large studies just published last month,

"most supplements do not prevent chronic disease or death, their use is not justified, and they should be avoided."

Save your money. Or better yet, if you must spend it, buy a bit more fresh fruit. You'll be healthier for it.

1 comment:

Living in Wisconsin and being extremely covered when I shovel snow, I have been (at doctor’s recommendation) taking Vit D in winter. Also in summer as I am extremely sun screened when outdoors (I have vitiligo).

I will discuss these findings with her at next visit and thanks for the heads up!